Ground fault interrupt and usb power supply electrical wiring device

ABSTRACT

An electrical wiring device including a ground fault interrupt assembly, the ground fault interrupt assembly comprising a ground fault interrupt circuit, being formed on a first printed circuit board, and a trip mechanism, the ground fault interrupt circuit being configured to detect a differential current between the line conductor and the neutral conductor and to trigger the trip mechanism to electrically decouple the plurality of line terminals from the plurality of load terminals, according to a predetermined criterion, based, at least in part, on the different current; and a USB power supply circuit being formed on a second printed circuit board disposed within the compartment, the USB power supply circuit providing to the at least one USB port, wherein the first printed circuit board and the second printed circuit board are separated by a distance within the inner compartment.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 17/088,785 filed on Nov. 4, 2020, which claims priority to andthe benefit of U.S. Provisional Patent Application No. 62/930,185 filedon Nov. 4, 2019 and U.S. Provisional Patent Application No. 63/063,641filed on Aug. 10, 2020, the entireties of which are incorporated hereinby reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to wiring devices and, more specifically,to a ground fault interrupt electrical wiring device with a USB powersupply.

2. Description of the Related Art

The proliferation of mobile devices has created a widespread need forreadily available charging ports. Nearly every mobile device can becharged with a charging cable that has a USB connector on one end and amicro USB or lightning connector on the other. The need for readilyavailable charging ports can thus be met by USB ports provided in anelectrical wiring device.

Such electrical devices can be equipped to have ground fault protection.Ground faults occur for several reasons. First, the hot conductor maycontact ground if the electrical wiring insulation within a load circuitbecomes damaged. This scenario represents a shock hazard. For example,if a user comes into contact with a hot conductor while simultaneouslycontact ground, the user will experience a shock. A ground fault mayalso occur when the equipment comes in contact with water. A groundfault may also result from damaged insulation within the electricalpower distribution system.

A ground fault creates a differential current between the hot conductorand the neutral conductor. Under normal operating conditions, thecurrent flowing in the hot conductor should equal the current in theneutral conductor. Accordingly, GFCIs are typically configured tocompare the current in the hot conductor to the return current in theneutral conductor by sensing the differential current between the twoconductors. When the differential current exceeds a predeterminedthreshold, usually about 6 mA, the GFCI typically responds byinterrupting the circuit. Circuit interruption is typically effected byopening a set of contacts disposed between the source of power and theload. The GFCI may also respond by actuating an alarm of some kind.

However, the combination of a ground fault interrupt and theaccompanying electromechanical assembly for separating the contactsrequires considerable space within the housing of an electrical wiringdevice. The addition of a USB power supply for supplying power to theUSB port can result in an electrical wiring device with a relativelylarge profile. The electrical wiring device housing must remain withincertain limits to fit into a standard wall box and to avoid taking uptoo much space within a wall.

But measures to more compactly fit the USB power supply together withthe ground fault interrupt protective device can exacerbate heatmanagement issues of the USB power supply and ground fault interruptcircuit, as heat-generating components are necessarily positioned nearone another to minimize the profile of the electrical wiring device.More specifically, various components of the USB power supply and theground fault interrupt circuit, such as a bridge rectifier,microcontroller or transformer, (these are only provided as examplecomponents, as the various components included can vary depending on theparticular example USB power supply and ground fault interrupt circuit)produce a relatively large amount of heat. When these components areused together in a compact housing, the heat produced by each can causethe electrical wiring device to overheat.

Accordingly, there is a need for a ground fault interrupt electricalwiring device with a USB charging port that is relatively compact whilemanaging the heat of the USB power supply circuit and ground faultinterrupt circuit.

BRIEF SUMMARY OF THE INVENTION

The examples described herein can be combined in any way technicallypossible.

According to an aspect, an electrical wiring device includes: aplurality of line terminals including a hot line terminal and a neutralline terminal, wherein the plurality of line terminals are configured tobe coupled to an AC electrical distribution system; a plurality of loadterminals comprising a hot load terminal and a neutral load terminal; aline conductor electrically coupling the hot line terminal to the hotload terminal; a neutral conductor electrically coupling the neutralline terminal to the neutral load terminal; a hot receptacle contact inelectrical contact with the hot line terminal when in a reset state andneutral receptacle contact in electrical contact with the neutral lineterminal when in the reset state, wherein the hot receptacle contact andthe neutral receptacle contact are dimensioned and positioned to receiveplug blades of a load plug; a universal serial bus (USB) receptacleconfigured to receive a USB adapter; a housing defining an innercompartment, wherein the line conductor, the neutral conductor, the hotreceptacle contact, the neutral receptacle contact, and the USBreceptacle are at least partially disposed in the inner compartment, aground fault interrupt assembly disposed within the inner compartment,the ground fault interrupt assembly comprising a ground fault interruptcircuit, being formed on a first printed circuit board, and a tripmechanism, the ground fault interrupt circuit being configured to detecta differential current between the line conductor and the neutralconductor and to trigger the trip mechanism to electrically decouple theplurality of line terminals from the plurality of load terminals,according to a predetermined criterion, based, at least in part, on thedifferent current; and a USB power supply circuit being formed on asecond printed circuit board disposed within the inner compartment, theUSB power supply circuit providing to the USB receptacle, wherein thefirst printed circuit board and the second printed circuit board areseparated by a distance within the inner compartment.

In an example, the electrical wiring device further includes ametal-oxide varistor being in common electrical contact with the groundfault interrupt circuit and the USB power supply circuit to absorbvoltage transients in either the ground fault interrupt circuit or theUSB power supply circuit.

In an example, the leads of the metal-oxide varistor extend through thefirst printed circuit board to the second printed circuit board orthrough the second printed circuit board to the first printed circuitboard.

In an example, the ground fault interrupt circuit is electricallyinsulated from the first printed circuit board by an insulativesubstrate disposed between the first printed circuit board and thesecond printed circuit board, wherein the insulative substrate iscomprised of a material having a resistivity greater than ambient air.

In an example, a first surface of the insulative substrate is disposedadjacent to the USB power supply circuit, wherein at least one componentof the USB power supply circuit is seated within a recess of theinsulative substrate, the recess being dimensioned to receive the atleast one component.

In an example, a second surface of the insulative substrate is disposedadjacent to the USB power supply circuit, wherein at least one componentof the USB power supply circuit is seated within a recess of theinsulative substrate, the recess being dimensioned to receive the atleast one component.

In an example, the electrical wiring device further includes a secondhot receptacle contact in electrical contact with the hot line terminaland a second neutral receptacle contact in electrical with the neutralline terminal.

In an example, the hot receptacle contact is in electrical contact withthe second hot receptacle contact by a first fixed contact bridgeextending between the hot receptacle contact and the second hotreceptacle contact, wherein the neutral receptacle contact is inelectrical contact with the second neutral receptacle contact by asecond fixed contact bridge extending between the neutral receptaclecontact and the second neutral receptacle contact, wherein the firstfixed contact bridge and the second fixed contact bridge arerespectively diverted toward a perimeter of the housing, wherein atleast one of a USB receptacle printed circuit board upon which the USBreceptacle is mounted, the USB receptacle, the ground fault interruptassembly, or the USB power supply circuit is, at least in part, disposedbetween the first fixed contact bridge and the second fixed contactbridge.

In an example, the USB power supply circuit comprises a transformer,wherein the second printed circuit board includes a first side and asecond side, wherein the first side faces the ground fault interruptassembly, wherein the second side faces away from the ground faultinterrupt assembly, wherein the transformer is disposed on the secondside of the second printed circuit board.

In an example, each of the components of the USB power supply circuitare disposed on the second side.

In an example, the USB power supply circuit comprises a controller and abridge rectifier, wherein the controller is separated from the bridgerectifier of by a distance of at least 15 mm.

In an example, the ground fault interrupt assembly is disposed betweenthe USB power supply circuit and a front cover, wherein the USB powersupply circuit is electrically connected to the USB receptacle by aconductive wire extending past the ground fault interrupt assembly andbetween the line conductor and the neutral conductor.

In an example, the USB power supply circuit is in electrical contactwith the hot load terminal and the neutral load terminal to receivepower when the electrical wiring device is in the reset state.

In an example, the USB power supply circuit is in electrical contactwith the hot line terminal and the neutral line terminal.

In an example, the line conductor and the neutral conductor arecomprised of a material having a conductivity at least 35% IACS.

In an example, the line conductor and the neutral conductor arecomprised of a brass material.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

The present invention will be more fully understood and appreciated byreading the following Detailed Description in conjunction with theaccompanying drawings, in which:

FIG. 1 is a perspective view of a protective device having a groundfault interrupt assembly and a USB power supply, according to anexample.

FIG. 2 is an exploded view of a protective device having a ground faultinterrupt assembly and a USB power supply, according to an example.

FIG. 3 is a perspective interior view of a portion of a protectivedevice having a ground fault interrupt assembly and a USB power supply,according to an example.

FIG. 4 is an exploded view of an insulative substrate and USB PCB,according to an example.

FIG. 5 is a perspective interior view of a portion of a protectivedevice having a ground fault interrupt assembly and a USB power supply,according to an example.

FIG. 6 is a perspective interior view of a portion of a protectivedevice having a ground fault interrupt assembly and a USB power supply,according to an example.

FIG. 7 is a side interior view of a protective device having a groundfault interrupt assembly and a USB power supply circuit, according to anexample.

FIG. 8 is a perspective interior view of a portion of a protectivedevice having a ground fault interrupt assembly and a USB power supply,according to an example.

FIG. 9 is a perspective interior view of a portion of a protectivedevice having a ground fault interrupt assembly and a USB power supply,according to an example.

FIGS. 10A and 10B are a schematic of a ground fault interrupt circuit,according to an example.

FIGS. 11A and 11B are a schematic of a USB power supply circuit,according to an example.

DETAILED DESCRIPTION OF THE INVENTION

Aspects of the various examples and certain features, advantages, anddetails thereof, are explained more fully below with reference to thenon-limiting examples illustrated in the accompanying drawings.Descriptions of well-known structures are omitted so as not tounnecessarily obscure the invention in detail. It should be understood,however, that the detailed description and the specific non-limitingexamples, while indicating aspects of the invention, are given by way ofillustration only, and are not by way of limitation. Varioussubstitutions, modifications, additions, and/or arrangements, within thespirit and/or scope of the underlying inventive concepts will beapparent to those skilled in the art from this disclosure. A 15 ampprotective wiring device is shown and described herein with respect tothe illustrated embodiments. Embodiments of the present inventionsimilarly apply to a 20 amp protective wiring device (as well as otherprotective wiring devices identified herein), as should be understoodand appreciated by a person of ordinary skill in the art in conjunctionwith a review of this disclosure (i.e., the front cover and neutral sidecontacts are structurally different, otherwise, embodiments of theinvention are structurally and functionally the same).

Reference will now be made in detail to the present exemplaryembodiments of the invention, examples of which are illustrated in theaccompanying drawings. Wherever possible, the same reference numberswill be used throughout the drawings to refer to the same or like parts.Various parts/elements of the protective device of embodiments of thepresent invention are first identified below and illustrated in theaccompanying drawings. Many of the parts/elements are conventional,should be understood by a person of ordinary skill in the art inconjunction with a review of this disclosure, and are not necessarilyfurther discussed in detail beyond being identified and represented incertain Figures. The structure, configuration, and positioning withrespect to other particular parts/elements/assemblies in the assembledprotective wiring device as a whole, and/or functionality of otherparticular parts/elements/assemblies are unique and inventive. Suchother parts/elements/assemblies are described in further detail below inaddition to the being identified and represented in certain Figures.

An example of the protective wiring device of the present invention isshown in FIG. 1 and is designated generally throughout by referencenumeral 10. FIG. 1 depicts a perspective view of an example assembledprotective device 10 having multiple outlet receptacles and USB portsand numerous features to both minimize the profile of the protectivedevice 10 and to manage the heat generated by the USB power supply andthe ground fault interruption circuit. These features will be describedin detail in this disclosure. Many of these features can be implementedindependent of one another (that is, to the extent technically possible,certain examples of protective device 10 can employ some of thesefeatures but not others). Further, many of these features can beemployed to minimize the profile or to manage heat in electrical wiringdevices besides protective device 10; indeed, many can be employedoutside of an electrical wiring device with both a ground faultinterrupt assembly and a USB power supply and USB port. For example,many of these features can be employed in any ground fault interruptelectrical wiring device (where a USB power supply and USB port areomitted), likewise many of these features can be employed in anyelectrical wiring device having an DC power supply and charging port(rather than only a USB power and port). Further, although many of theseinventive features are shown with a particular example of a ground faultinterrupt assembly, many of these features can be used in any suitableground fault interrupt assembly, as appropriate for the particularground fault interrupt assembly used.

Certain structural and functional aspects of embodiments of the presentinvention are similar to embodiments of the protective wiring devicedescribed and illustrated in U.S. application Ser. No. 16/967,331 filedon Aug. 4, 2020 and titled “Protective Wiring Device,” which is herebyincorporated by reference in its entirety, describes many features ofthe functioning of the ground fault interrupt assembly and theelectrical wiring device in general. To the extent that these groundfault assembly or other features are the same as the features ofprotective device 10, a detailed explanation has been omitted to avoidneedlessly obscuring the inventive features, and U.S. application Ser.No. 16/967,331 should be referred for descriptions of their structureand operation. Furthermore, U.S. application Ser. No. 16/967,331 itselfrelies upon various patent for the explanation of additional features.These patents are likewise incorporated by reference in their entiretyfor additional explanation and embodiments and include: U.S. Pat. Nos.9,437,386, 9,543,715 and 9,893,456.

As shown, the protective device 10 includes a housing having a frontcover 12, a back-body 14 and a separator 16, which together define aninterior compartment. The front cover 12 includes outlet receptacles12-1, 12-2 which are configured to accept the hot, neutral and groundblades of a corded plug, and USB ports 12-3, 12-4 which are configuredto accept a USB plug (to, e.g., charge a mobile device). The back-body14 includes line screw terminals 102 and load screw terminals 202 thatallow the device to be connected to a source of AC power and a loadcircuit, respectively.

Turning to FIG. 2 , a perspective exploded view of the protective device10 of an example of the present invention is shown. Starting from thetop portion of the device, the various parts/elements are nowidentified: test button 18, front cover 12, reset button 17, resetstructure 17-1, reset break spring 17-2, ground strap 2, USB receptaclePCB 303 upon which are mounted a type-A USB receptacle 303-1, and a typeB USB receptacle 303-2, a hot receptacle terminal 22-1 including hotoutlet receptacle contacts 22-10 and fixed contact bridge 22-12, aneutral receptacle terminal 22-2 including neutral outlet receptaclecontacts 22-20 and fixed contact bridge 22-22, light pipe 204-3,separator 16, test contact arm 234, electromechanical assembly 200(alternatively referred to as “ground fault interrupt assembly”)including electromechanical PCB 201 and trip mechanism 203 (whichincludes latch block 220 and latch 230), hot line contact arm 104-1,neutral line contact arm 104-2, hot line terminal 102-1, neutral lineterminal 102-2, hot load terminal arm 202-1, neutral load terminal arm202-2, spacer 301 (alternatively referred to “insulative substrate”),USB printed circuit board 302, back body 14 (which is elongated in thisexample to accommodate the USB printed circuit board 302 and spacer301), and assembly screws 5.

The exploded view of FIG. 2 further depicts an alternative example offront cover 12: front cover 12′ and front cover 12″. Front cover 12′include USB ports 12-3 and 12-4 for two type A USB receptacles 303-1;whereas front cover 12″ includes USB ports 12-3 and 12-4 for two type CUSB receptacles 303-2. Front cover 12′ interfaces with USB receptacles303-2 of USB printed circuit board 303′. Front cover 12″ interfaces withUSB receptacles 303-1 of USB printed circuit board 303″.

The ground fault interrupt circuit 1000, which is described brieflybelow in connection with FIG. 10 , detects a ground fault and, togetherwith trip mechanism 203, electrically decouples hot line terminal 102-1and neutral line terminal 102-2 from hot load terminal arm 202-1 andneutral load terminal arm 202-2, respectively. Ground fault interruptcircuit 1000 is formed on electromechanical PCB 201, upon which tripmechanism 203 is also mounted.

The USB power supply circuit 1100 converts the AC mains voltage, presentacross the hot line terminal 102-1 and neutral line terminal 102-2, to aUSB voltage provided to USB receptacles 303-1, 303-2 for powering aconnected device. The USB power supply circuit 1100 described brieflybelow in connection with FIG. 11 , is formed on USB PCB 302. Both theUSB PCB 302 and the electromechanical PCB 201 are disposed within aninterior compartment of housing (e.g., within back body 14).

FIG. 3 depicts perspective view of ground fault assembly 200, USB PCB302, together with hot line contact arm 104-1, neutral line contact arm104-2, hot line terminal 102-1, neutral line terminal 102-2, hot loadterminal arm 202-1, neutral load terminal arm 202-2, and spacer 301. Asshown, electromechanical PCB 201 is positioned some distance D from USBPCB 302. Distance D generally ensures that the ground fault interruptcircuit 1000 is electrically insulated from the USB power supply circuit1100. To minimize the size of distance D, and thus minimize the profileof protective device 10, an insulative substrate 301 can be positionedbetween electromechanical PCB 201 and USB PCB 302. The insulativesubstrate 301 can be formed of any suitable material having aresistivity greater than that of the ambient air—e.g., rubber, plastic—and can thus be thinner than the width of an air gap required toinsulate the ground fault interrupt circuit 1000 from the USB powersupply circuit 1100. In an alternative example, rather than usinginsulative substrate 301, electromechanical PCB 201 and USB PCB 302 canbe separated only by the air gap, although this will require a slightlylarger profile of protective device 10 as the air gap must be largerthan the thickness of insulative substrate 301 in order to ensure thatelectromechanical PCB 201 and USB PCB 302 are electrically insulated.

It should be understood that in certain examples, some of which aredescribed below, there may be some electrical communication betweenground fault interrupt circuit 1000 and USB power supply circuit 1100(e.g., to supply the AC mains voltage to the USB power supply circuit).It should thus be understood that, for the purposes of this disclosure,maintaining electrical insulation between the ground fault interruptcircuit 1000 and USB power supply circuit 1100 entails preventingelectrical contact between the respective circuits, except fromconnections that are designed to occur. Stated differently, theinsulative substrate 301 is positioned to prevent unwanted electricalcontact that would otherwise occur between the components of the stackedground fault interrupt circuit 1000 and USB power supply circuit 1100.

As shown in FIG. 4 , to further minimize the distance D betweenelectromechanical PCB 201 and USB PCB 302, insulative substrate 301 candefine in its surface one or more recesses for receiving one or morecomponents of either electromechanical PCB 201 or USB PCB 302, thuspermitting electromechanical PCB 201 to be positioned closer to USB PCB302. For example, recesses 301-2, 301-3 can be defined within theotherwise planar surface of the insulative substrate 301 to receivecomponents such as jumpers and solder from electromechanical PCB 201 atrecess 301-3 or a diode from USB PCB 302 at recess 301-2, as shown inFIG. 4 . This is only provided as an example, however, and it should beunderstood that in various alternative examples, any number of recessescan each receive any number of any types of components to ensure thatelectromechanical PCB 201 is positioned as close as possible to USB PCB302 while providing insulation between the respective circuits.Furthermore, as shown in FIG. 4 spacer 301 can be fitted to USB PCB 302via snap fittings 301-6 to ensure that spacer 301 and USB power supply302-1 remain held together compactly.

Both ground fault interrupt circuit 1000 and USB power supply circuit1100 employ a metal-oxide varistor (MOV) to protect against transientvoltages (i.e., voltage surges) that would otherwise damage ground faultinterrupt circuit 1000 or the USB power supply circuit 1100. Because theMOV is a fairly large component, in order to reduce the size of theground fault interrupt circuit and USB power supply circuit 1100 (andthus reduce the overall profile of protective device 10), a single MOVcan be commonly shared between the ground fault interrupt circuit 1000and the USB power supply circuit 1100. Stated differently, a single MOVcan be commonly disposed between the hot and neutral input terminals ofboth the ground fault interrupt circuit 1000 and the USB power supplycircuit 1100 to shunt current from each in the event of transientvoltage. This can be accomplished by providing electrical contactbetween the hot inputs of both the ground fault interrupt circuit andthe USB power supply circuit and one lead of the MOV and electricalcontact between the neutral inputs of both the ground fault interruptcircuit and the USB power supply circuit and the other lead of the MOV.In this way, excess current from a voltage transient present in the ACmains voltage, will be shunted by the MOV common to both the groundfault interrupt circuit 1000 and the USB power supply circuit. Referringbriefly to FIGS. 10 and 11 , in this example, MOV2 of FIG. 10 and MOV1of FIG. 11 are implemented as the same component.

Returning to FIG. 3 , in order to electrically connect the same MOV 204to both the ground fault interrupt circuit 1000 and the USB power supplycircuit 1100, leads 204-1, 204-2 can be permitted to extend through theelectromechanical PCB 201 to USB PCB 302, or, otherwise, from USB PCB302 to electromechanical PCB 201. Where the leads of the MOV 204 wouldnormally be trimmed when the MOV 204 is soldered to eitherelectromechanical PCB 201 or USB PCB 302, the leads can be leftuntrimmed, thus spanning the distance D between the electromechanicalPCB 201 and USB PCB 302, and allowing it to make electrical contact withboth ground fault interrupt circuit 1000 and USB power supply circuit1100. For example, as shown in FIG. 3 , the leads of a MOV can extendthrough through-holes 201-1, 201-2 (shown in FIGS. 5 and 6 ) of theelectromechanical PCB 201 across distance D separating electromechanicalPCB 201 from USB PCB 302, and through the through-holes 302-1, 302-2(shown in FIG. 4 ) of USB PCB 302. This example further can serve thedual purpose of bringing power from the hot and neutral terminals of theground fault interrupt circuit 1000 to the hot and neutral terminals ofthe USB power supply circuit 1100. Otherwise, the USB power supplycircuit would require a separate connection to the hot and neutral inputterminals (e.g., through tabs on hot and neutral input terminals).Further, in this example, holes 301-4, 301-5 (shown in FIG. 4 ) definedin spacer 301 can further act to guide leads 204-1, 204-2 to USB PCB302, and to permit leads 204-1, 204-2 to pass through spacer 301 to USBPCB 302 (where they would otherwise be blocked).

Alternatively, rather than employing the leads of the MOV 204, separateconductors (e.g., wires) can be used to make common electrical contactbetween the MOV 204 and both the ground fault interrupt circuit 1000 andthe USB power supply circuit 1100. For example, MOV 204 can be solderedto one of the ground fault interrupt circuit 1000 and the USB powersupply circuit 1100 and connected by a wire to the other.

To further manage the heat produced by various components of the USBsupply circuit, at least one component of the USB supply circuit can bepositioned on a side of the USB PCB 302 facing away fromelectromechanical PCB 201. In the example of FIG. 7 , certain componentsof the USB power supply circuit 1100 are positioned on the side of theUSB PCB 302, i.e., on the side labeled 302B, facing away fromelectromechanical PCB 201. This placement of USB power supply circuit1100 components functions to manage the heat produced by thosecomponents by situating the USB PCB 302 between the heat-generatingcomponents and the electromechanical PCB 201, thus thermally insulatingthe components of USB power supply circuit 1100 from the components ofthe ground fault interrupt circuit 1000. In addition, this positioningof the components of the USB power supply circuit 1100 increases thedistance between the components of the USB power supply circuit 1100 andthe components of the ground fault interrupt circuit 1000.

In the example of FIG. 7 , only certain components—e.g., those thatgenerate the most heat—are positioned on side 302B. For example,transformer 1102 (designated as T1 in FIG. 11 ) can be positioned onside 302B alongside various other components. However, as shown, otherheat-generating components, such as bridge rectifier 1103 (designated asBR1 in FIG. 11 ), and controller 1104 (designated as U1 in FIG. 11 ),are situated on side 302A. These components are not positioned on side302B in order to space them from transformer 1002 and to better managespacing on USB PCB 302, where there is limited surface area to positioncomponents. In alternative example, all components of USB power supplycircuit 1100 are positioned on side 302B in order to space them from thecomponents of ground fault interrupt circuit 1000.

Likewise, some or all components of the ground fault interrupt circuit1000 can be positioned on side 201A of electromechanical PCB 201 facingaway from USB PCB 302. As shown in FIG. 6 , certain components of theground fault interrupt circuit 1000 are faced toward USB PCB 302;however, in alternative examples, some of these components, or all ofthese components, can be positioned on the opposite side ofelectromechanical PCB 201 in order to increase the distance between thecomponents of the USB power supply circuit 1100 and the ground faultinterrupt circuit 1000 and to position the electromechanical PCB 201 asa thermal insulator.

Furthermore, the components on a single side of USB PCB 302 andelectromechanical PCB 201 can be spaced to spread the heat generatedacross the PCB rather than concentrating it in one place. This can beseen, for example, by the relative positions of bridge rectifier 1103and controller 1104, which are spaced across side 302A of USB PCB 302 toavoid concentrating the heat generated by each in a single location. Inan example, the bridge rectifier 1103 and controller 1104 can be spacedby a distance of at least 15 mm to spread the heat generated across USBPCB 302. (In an example, a distance of 20 mm was shown to effectivelyspread the heat generating components across the surface of the USB PCB302.)

To further manage heat, various components of protective device 10 canbe comprised of materials having a thermal conductivity of at least 35%IACS. Such components can be, for example, hot line terminal 102-1,neutral line terminal 102-2, hot contact arm line 104-1, neutral contactline arm 104-2, hot load terminal arm 202-1, neutral load terminal arm202-2, and jumpers 201-3. The material can, for example, be 7025 brass(which has a conductivity of 40% IACS), although it is conceivable thatother materials could be used.

Turning now to FIG. 8 , a perspective view of the protective device 10shows the separator 16, hot receptacle terminal 22-1, neutral receptacleterminal 22-2. As shown, hot receptacle terminal 22-1 includes a fixedcontact bridge 22-12 and neutral receptacle terminal 22-2 includes fixedcontact bridge 22-22. The fixed contact bridge 22-12 serves to provideelectrical contact between the hot outlet receptacle contacts 22-10, andfixed contact bridge 22-22 serves to provide electrical contact betweenthe neutral outlet receptacle contacts 22-20. Thus, by placing hotreceptacle terminal 22-1 in electrical contact with hot line contact arm104-1 (and hot load terminal arm 202-1) and by placing neutralreceptacle terminal 22-2 in electrical contact with neutral line contactarm 104-2 (and neutral load terminal arm 202-2), the AC mains voltagewill exist between the hot outlet receptacle contacts 22-10 and theneutral outlet receptacle contacts 22-20 as long as the protectivedevice 10 is in the reset state. Once the protective device 10 entersthe tripped state and trip mechanism 203 interrupts electrical contactbetween the hot line contact arm 104-1 and hot receptacle terminal 22-1and between neutral line contact arm 104-2 and neutral receptacleterminal 22-2, the hot receptacle terminal 22-1 and the neutralreceptacle terminal 22-2 will cease to be powered.

In order to further reduce the profile of protective device 10 fixedcontact bridge 22-12 and fixed contact bridge 22-22 can be divertedtoward the sidewalls of back body 14 (i.e., at an angle perpendicular toor oblique to axis A-A), allowing USB receptacle PCB 303 (andconsequently, USB receptacles 303-1 and 303-2) to be disposed betweenfixed contact bridge 22-12 and fixed contact bridge 22-22 and, thereby,to be seated deeper in within back body 14. Stated differently, bydiverting the fixed contact bridge 22-12 and fixed contact bridge 22-22toward the sidewalls of housing—between hot outlet receptacle contacts22-10 and neutral outlet receptacle contacts 22-20—fixed contact bridge22-12 and 22-22 can be disposed to the sides of electromechanicalassembly 200, and thus do not contribute to the profile of protectivedevice 10. In the example shown, the diverted fixed contact bridge 22-12and fixed contact bridge 22-22 can each be diverted toward a respectivesidewall of back body 14, such that no other components are positionedbetween the diverted fixed contact bridge 22-12 and the sidewall of backbody 14 and between fixed contact bridge 22-22 and the sidewall of backbody 14. In an alternative example, electromechanical PCB 201 and/or USBPCB 302 can be positioned between the diverted fixed contact bridge22-12 and fixed contact bridge 22-22 rather than, or in addition to, theelectromechanical USB receptacle PCB 303.

As shown in FIG. 9 , the output voltage of the USB power supply circuit1100 can be provided to the USB receptacle 303-1, 303-2 via a conductivewire 302-3. To further minimize space requirements, the conductive wire302-3 can be threaded between hot load terminal arm 202-1 and neutralload terminal arm 202-2. Conductive wire 302-3 can be maintained inposition via an aperture 301-8 defined at the end of spacer 301.

It should be understood that any suitable ground fault interrupt circuitcan be employed to trigger trip mechanism 203, a brief description of anexample ground fault interrupt circuit 1000 is shown for the purpose ofcompleteness. The protective device 10 includes a differentialtransformer 1002 which is configured to sense load-side ground faults,i.e. ground faults located in loads connected to load terminals orreceptacle contacts. Transformer 1004 is configured as a groundedneutral transmitter that is configured for grounded-neutral faultdetection. Both differential transformer 1002 and grounded-neutraltransformer 1004 are electrically coupled to the fault detector U1.Detector U1 receives power from half wave rectification diode D1,inputting power to Vs pin 3 of detector U1 and further processed byinternal regulation circuit. The output of the detector U1 is connectedto the control input of SCR Q1. When SCR Q1 is turned ON, the solenoidcoil K1A is energized to actuate the trip mechanism 203 such that thetrip mechanism 203 opens and switch K1B closes. Solenoid coil K1Aremains energized for a time period that is typically less than about 25milliseconds. When the trip mechanism 203 trips, the line terminals aredisconnected from their respective load terminals or receptaclecontacts. After the fault condition has been eliminated, the tripmechanism 203 may be reset by way of reset button 17. MCU U2 providesadditional functionality to monitor detector U1. MCU U2 is responsiblefor self-test, miswire detection and indicating status. Unlike detectorU1 which only receives power and operates within the positive halfcycles, MCU U2 has power and functions throughout the entire line cycle(positive and negative). This is accomplished via half waverectification diode D4 and voltage regulator Q5, R5, D5, C12, where C12provides storage during the negative half cycle. MCU U2 controls FET Q2during self-test via Test GFCI node, where drain of Q2 is provided witha positive DC voltage via multiple IO via MCU U2. Various other IO ofMCU U2 are utilized for basic yet essential standard MCU practices suchas zero cross ZC monitoring, system power availability via RST node,programming nodes, etc. Some aspects of self-test and miswire test ofMCU U2 will be described in detail below, with reference, asappropriate, to related patents. Other aspects of MCU U2 are known anddo not require a detailed explanation here.

The differential transformer 1002 includes a secondary winding which iscoupled to the fault detector U1 accompanied by noise filteringcircuitry. The differential transformer 1002 senses the currentdifferential between the hot and neutral conductors and provides asensor signal to the ground fault detector U1 via the (IN−, IN+) inputs.When the differential current (sensor signal) exceeds a predeterminedthreshold value, the fault detector U1 should cause the SCR output to goHIGH.

The grounded neutral transmitter 1004 is configured to detect a groundedneutral condition. (The line neutral conductor is typically grounded inthe electrical circuit at the panel— this does not constitute a groundedneutral fault condition). The neutral transmitter 1004 is configured tocouple equal signals into the hot, neutral and self test (3rd wire)conductors. Because the differential transformer 1002 is configured tosense a current differential, the equal signals provided by the groundedneutral transmitter 1004 effectively cancel each other out. On the otherhand, a grounded neutral condition does occur when the load neutralconductor (i.e., the conductor that is connected to the load neutralterminal or the neutral receptacle contact) is accidentally grounded.This creates a parallel conductive path (relative to the neutral returnpath) between the neutral line terminal and neutral load terminal. As aresult, another signal circulates around this current loop and iscoupled onto the neutral conductor (but not the hot conductor) to createa differential current. The differential transformer 1002 senses thedifferential current between the hot and neutral conductors and thedetector U1 generates a fault detection signal to actuate SCR Q1,energize solenoid coil K1A and trip the trip mechanism 203.

Any suitable AC/DC power supply circuit may be used as the USB powersupply circuit. An example of such a power supply circuit is shown inFIG. 11 as USB power supply circuit 1100. In this example, the input ACmains voltage is received at terminals AC1 and AC2. USB power supplycircuit 1100 converts this input voltage to a 5V output voltage atterminals 5V_IN and GND. This 5V output voltage is used as the busvoltage Vbus of the USB type A receptacle. This output voltage is onlyprovided as an example potential output voltage. Indeed, various typesof USB connectors are designed to supply different voltages and thus, inalternative examples, USB power supply circuit 1100 can be designed tosupply the voltage in keeping with the standard types of USB connectorsemployed in protective device 10. Alternatively, a separate output DC/DCoutput stage can be employed to further condition of the output of USBpower supply circuit 1100 in keeping with the requirements of the typeof USB receptacle employed.

In the example shown in FIG. 11 , USB power supply circuit 1100 receivesthe AC mains input signal which is rectified and filtered via bridgerectifier BR1, capacitors C20, C3, and inductor L2. The rectified andfiltered signal is input to transformer T1. Controller U1 which, in anexample, is a Power Integrations INN3165C power supply controller,operates in secondary side sensing and regulation the feedback signalappearing at pin 3 through the voltage divider of R14 and R15. U1contains an integral switching device (e.g., a MOSFET). While controllerU1 keeps MOSFET ON, current in the primary winding of transformer T1increases. During this time, current is prevented from flowing throughthe secondary winding of transformer T1 by MOSFET Q1, which iscontrolled by controller U1 (MOSFET Q1 serves as a secondary siderectifier. Generally, the MOSFET Q1 is preferred to the traditionaldiode due to its much lower on-state voltage, which results in lesspower loss and an increase in overall efficiency.) Once the controllerturns the integral MOSFET OFF, it, at the same time, turns MOSFET Q1.The energy stored in the primary winding from the MOSFET ON-time istransferred to the secondary winding of T1, which charges output filtercapacitor C14. (Capacitor C22 provides additional high-frequencyattenuation.) Once controller U1 again turns the integral MOSFET off,the load current is supplied from the output filter capacitor C14. Theintegral MOSFET, transformer T1, and MOSFET Q1 together form a variantof a flyback converter. The snubber circuit, consisting of diode D1,resistor R6, capacitor C18, and resistor R21 effectively clamps thevoltage and suppresses ringing on the drain of the MOSFET.

As described above, various output stages can be incorporated to furthercondition the output of USB power supply circuit 1100 for powering aType-A or Type-C USB circuit. In addition, various controllers can beemployed to communicate with the connected device as a dedicatedcharging port. For example, in addition to the above, a TexasInstruments TPS2513A dedicated charging port controller can be employedto monitor USB data voltage and automatically provide the correctelectrical signatures on the data lines for charging.

As described above, USB power supply circuit 1100 can, as describedabove, receive power from a MOV commonly shared between the ground faultinterrupt circuit 1000 and the USB power supply circuit 1100.Alternatively, tabs on the hot line terminal 102-1 and neutral lineterminal 102-2 can be in electrical contact with and supply power to theUSB power supply circuit 1100. Both of these methods for supplying powerto the USB power supply circuit 1100, place the USB power supply circuit1100 in electrical contact with the line-side of protective device 10.This is generally desirable, as it ensures that the high frequencyswitching of the USB power supply circuit 1100 will not cause nuisancetrips of the trip mechanism 203. In an alternative example, however, USBpower supply circuit 1100 can receive power from the load-side ofprotective wiring device (e.g., from tabs disposed at the ends of hotload terminal arm 202-1, neutral load terminal arm 202-2). While USBpower supply circuit 1100 is already NEC class 2 power supply, whichsupplies acceptable protection from electric shock, by supplying powerto the USB power supply circuit 1100 from the load-side, the USB powersupply circuit 1100, and consequently the USB receptacles, will bedisconnected from power in the event of a trip, providing redundantprotection methods.

Although a dual-USB dedicated charging port example is described in thisdisclosure, it should be understood that protective device 10 caninclude any number of USB ports. Furthermore, as mentioned above,various alternative examples can employ the features described herein inconjunction with charging ports besides USB charging ports. In addition,certain features of described herein can be used to improve the profilesize or heat management in devices that do not include power supplycircuits (e.g., in GFCI-only protective devices) or in devices that donot include ground fault interrupt protective circuits or mechanisms.

While several inventive embodiments have been described and illustratedherein, those of ordinary skill in the art will readily envision avariety of other means and/or structures for performing the functionand/or obtaining the results and/or one or more of the advantagesdescribed herein, and each of such variations and/or modifications isdeemed to be within the scope of the inventive embodiments describedherein. More generally, those skilled in the art will readily appreciatethat all parameters, dimensions, materials, and configurations describedherein are meant to be exemplary and that the actual parameters,dimensions, materials, and/or configurations will depend upon thespecific application or applications for which the inventive teachingsis/are used. Those skilled in the art will recognize, or be able toascertain using no more than routine experimentation, many equivalentsto the specific inventive embodiments described herein. It is,therefore, to be understood that the foregoing embodiments are presentedby way of example only and that, within the scope of the appended claimsand equivalents thereto; inventive embodiments may be practicedotherwise than as specifically described and claimed.

All references, including publications, patent applications, andpatents, cited herein are hereby incorporated by reference to the sameextent as if each reference were individually and specifically indicatedto be incorporated by reference and were set forth in its entiretyherein.

All definitions, as defined and used herein, should be understood tocontrol over dictionary definitions, definitions in documentsincorporated by reference, and/or ordinary meanings of the definedterms.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. The terms “comprising,” “having,” “including,” and “containing”are to be construed as open-ended terms (i.e., meaning “including, butnot limited to,”) unless otherwise noted. The term “connected” is to beconstrued as partly or wholly contained within, attached to, or joinedtogether, even if there is something intervening.

As used herein in the specification and in the claims, the phrase “atleast one,” in reference to a list of one or more elements, should beunderstood to mean at least one element selected from any one or more ofthe elements in the list of elements, but not necessarily including atleast one of each and every element specifically listed within the listof elements and not excluding any combinations of elements in the listof elements. This definition also allows that elements may optionally bepresent other than the elements specifically identified within the listof elements to which the phrase “at least one” refers, whether relatedor unrelated to those elements specifically identified. Thus, as anon-limiting example, “at least one of A and B” (or, equivalently, “atleast one of A or B,” or, equivalently “at least one of A and/or B”) canrefer, in one embodiment, to at least one, optionally including morethan one, A, with no B present (and optionally including elements otherthan B); in another embodiment, to at least one, optionally includingmore than one, B, with no A present (and optionally including elementsother than A); in yet another embodiment, to at least one, optionallyincluding more than one, A, and at least one, optionally including morethan one, B (and optionally including other elements); etc.

It should also be understood that, unless clearly indicated to thecontrary, in any methods claimed herein that include more than one stepor act, the order of the steps or acts of the method is not necessarilylimited to the order in which the steps or acts of the method arerecited.

Approximating language, as used herein throughout the specification andclaims, may be applied to modify any quantitative representation thatcould permissibly vary without resulting in a change in the basicfunction to which it is related. Accordingly, a value modified by a termor terms, such as “about” and “substantially”, are not to be limited tothe precise value specified. In at least some instances, theapproximating language may correspond to the precision of an instrumentfor measuring the value. Here and throughout the specification andclaims, range limitations may be combined and/or interchanged; suchranges are identified and include all the sub-ranges contained thereinunless context or language indicates otherwise.

The recitation of ranges of values herein are merely intended to serveas a shorthand method of referring individually to each separate valuefalling within the range, unless otherwise indicated herein, and eachseparate value is incorporated into the specification as if it wereindividually recited herein.

All methods described herein can be performed in any suitable orderunless otherwise indicated herein or otherwise clearly contradicted bycontext. The use of any and all examples, or exemplary language (e.g.,“such as”) provided herein, is intended merely to better illuminateembodiments of the invention and does not impose a limitation on thescope of the invention unless otherwise claimed.

No language in the specification should be construed as indicating anynon-claimed element as essential to the practice of the invention.

In the claims, as well as in the specification above, all transitionalphrases such as “comprising,” “including,” “carrying,” “having,”“containing,” “involving,” “holding,” “composed of,” and the like are tobe understood to be open-ended, i.e., to mean including but not limitedto. Only the transitional phrases “consisting of” and “consistingessentially of” shall be closed or semi-closed transitional phrases,respectively, as set forth in the United States Patent Office Manual ofPatent Examining Procedures, Section 2111.03.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the present inventionwithout departing from the spirit and scope of the invention. There isno intention to limit the invention to the specific form or formsdisclosed, but on the contrary, the intention is to cover allmodifications, alternative constructions, and equivalents falling withinthe spirit and scope of the invention, as defined in the appendedclaims. Thus, it is intended that the present invention cover themodifications and variations of this invention provided they come withinthe scope of the appended claims and their equivalents.

What is claimed is:
 1. An electrical wiring device comprising: aplurality of line terminals including a hot line terminal and a neutralline terminal, wherein the plurality of line terminals are configured tobe coupled to an AC electrical distribution system; a plurality of loadterminals comprising a hot load terminal and a neutral load terminal; aline conductor electrically coupling the hot line terminal to the hotload terminal; a neutral conductor electrically coupling the neutralline terminal to the neutral load terminal; a hot receptacle contact inelectrical contact with the hot line terminal when in a reset state andneutral receptacle contact in electrical contact with the neutral lineterminal when in the reset state, wherein the hot receptacle contact andthe neutral receptacle contact are dimensioned and positioned to receiveplug blades of a load plug; a universal serial bus (USB) receptacleconfigured to receive a USB adapter; a housing defining an innercompartment, wherein the line conductor, the neutral conductor, the hotreceptacle contact, the neutral receptacle contact, and the USBreceptacle are at least partially disposed in the inner compartment, aground fault interrupt assembly disposed within the inner compartment,the ground fault interrupt assembly comprising a ground fault interruptcircuit, being formed on a first printed circuit board, and a tripmechanism, the ground fault interrupt circuit being configured to detecta differential current between the line conductor and the neutralconductor and to trigger the trip mechanism to electrically decouple theplurality of line terminals from the plurality of load terminals,according to a predetermined criterion, based, at least in part, on thedifferent current; and a USB power supply circuit being formed on asecond printed circuit board disposed within the inner compartment, theUSB power supply circuit providing to the USB receptacle, wherein thefirst printed circuit board and the second printed circuit board areseparated by a distance within the inner compartment.